Obesity is a major public health issue as it enhances the risk of suffering several chronic diseases of increasing prevalence. Obesity results from an imbalance between energy intake and expenditure, associated with a chronic low-grade inflammation. It is known to contribute to the risk of developing type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), cancer, osteoarthritis and cardiovascular disease (CVD). Obesity results from a complex interaction between genetic and environmental factors, such as a high calorie diet, and lack of physical activity and recent research has also suggested that the gut microbiota may play a role in the development of obesity. An unbalanced diet rich in fat and/or carbohydrate is associated with triglyceride storage in adipose tissue, muscle, liver and the heart. Ectopic fat deposition, particularly in a central distribution, is also thought to contribute to a range of metabolic disorders such as hypertriglyceridaemia, hypertension, high fasting glucose and insulin resistance (IR).
Gut microbes are considered to contribute to body weight regulation and related disorders by influencing metabolic and immune host functions. The gut microbiota as a whole improves the host's ability to extract and store energy from the diet leading to body weight gain, while specific commensal microbes seem to exert beneficial effects on bile salt, lipoprotein, and cholesterol metabolism. The gut microbiota and some probiotics also regulate immune functions, protecting the host from infections and chronic inflammation. In contrast, dysbiosis and endotoxaemia may be inflammatory factors responsible for developing insulin resistance and body weight gain. In the light of the link between the gut microbiota, metabolism, and immunity, the use of dietary strategies to modulate microbiota composition is likely to be effective in controlling metabolic disorders. Although so far only a few preclinical and clinical trials have demonstrated the effects of specific gut microbes and prebiotics on biological markers of these disorders, the findings indicate that advances in this field could be of value in the struggle against obesity and its associated-metabolic disorders (Sanz et al. 2008).
Recent data, both from experimental models and from human studies, support the beneficial effects of particular food products with prebiotic properties on energy homeostasis, satiety regulation and body weight gain. Together, with data in obese animals and patients, these studies support the hypothesis that gut microbiota composition (especially the number of bifidobacteria) may contribute to modulate metabolic processes associated with syndrome X, especially obesity and diabetes type 2. It is plausible, even though not exclusive, that these effects are linked to the microbiota-induced changes and it is feasible to conclude that their mechanisms fit into the prebiotic effect. However, the role of such changes in these health benefits remains to be definitively proven. As a result of the research activity that followed the publication of the prebiotic concept 15 years ago, it has become clear that products that cause a selective modification in the gut microbiota's composition and/or activity(ies) and thus strengthens normobiosis could either induce beneficial physiological effects in the colon and also in extra-intestinal compartments or contribute towards reducing the risk of dysbiosis and associated intestinal and systemic pathologies (Roberfroid et al., 2010).
It would therefore be desirable to provide the art with a method that allows it to identify subjects early—ideally at risk—to put on weight (e.g. for instance after initiation of a weight loss program). In particular, it would be desirable to provide a method for predicting and/or quantifying the response of subjects to prebiotics in the prevention of diet induced weight gain, especially at an early stage after starting the administration of prebiotics.
Thus an object of the present invention is to provide a method that allows the early stratification of subjects according to whether or not they are likely to respond to a prebiotic-based intervention to prevent high fat diet induced or related weight gain.